1. Field of the Invention
The present invention relates to an electrophotographic copying apparatus of a slit exposure type and particularly to a copying apparatus having a book copy mode in which an original to be scanned for exposure is divided into a first area and a second area and those two areas are scanned to successively form individual copy image planes.
2. Description of the Prior Art
In general, when a book copy mode is selected, a scanning system scans two facing pages of a book by dividing those pages into separate areas and a copy operation is continuously performed to copy each page on an individual copy plane. An example of the operation in the book copy mode is hereinafter described with reference to FIG. 1.
In order to copy specified two facing pages of a book, i.e., an even-numbered page A and an odd-numbered page B, the opened book is placed on a glass document platen 16 of a copying apparatus so that copy operation is performed in the book copy mode. The first scanning is performed by an odd-numbered page scanning .alpha. for the odd-numbered page B succeeding the even-numbered page A, i.e., the odd-numbered scanning o for the range from an original reference point b to an original end point c based on scanning from an original reference point a to the original end point c. Subsequently, an even-numbered page scanning .beta. for the even-numbered page A preceding the odd-numbered page B, i.e., the even-numbered page scanning .beta. for the range from the original reference point a to the original reference point b based on scanning from the original reference point a to the original reference point b is performed.
After the above described scanning operations, a copy image based on the even-numbered page scanning .beta. is excluded from a copy image based on the odd-numbered page scanning .alpha. so that the copy image of the odd-numbered page B is obtained. As a result, copies of the pages according to the page numbers of the document are obtained.
However, if the book copy mode is selected in such a copying apparatus, it is generally not possible to use a copy mode set by automatic detection of a size of an original such as an automatic magnification selection mode or an automatic paper selection mode. This is because in most apparatus the original size detecting function can be performed only in the case of using an original in the form of a sheet. Accordingly, if the book copy mode for a thick original such as a book is selected in such an apparatus, the apparatus is controlled so that a mode based on automatic detection of an original size as described above cannot be selected.
On the other hand, there is also a demand for copying an original with a desired magnification or a desired paper size even in the book copy mode.
However, under the circumstances, since the automatic magnification selection mode or the automatic paper selection mode cannot be used in the book copy mode, it is only possible to take measures such as limited selection of a specified paper size or magnification in the book copy mode. Such measures cannot satisfy the demands of the user and often cause errors such as a defective copy image.